Polyvinyl alcohol-based electrospun matrix as a delivery system for nanoemulsion containing chalcone against Leishmania (Leishmania) amazonensis.

Cutaneous leishmaniasis is a worldwide public health problem. Conventional therapies, in addition to the high cost, have many adverse effects and cases of parasite's resistance. Chalcones are secondary metabolites precursors in the flavonoid pathway and can be obtained naturally, but with low yield from plant raw material. Thus, the use of synthetic chalcones has been a promising strategy for the development of molecules with leishmanicidal activity. Thus, this work aimed to develop a controlled release system of two synthetic chalcone (trans-chalcones and 3'-(trifluormethyl)-chalcone) using polyvinyl alcohol nanofibers (PVA) as scaffold. The association of chalcones to the nanofibers was made by nanoemulsions (NE) thereof, i.e., a colloidal system on a nanometric scale, which allows compounds with opposite polarities to remain miscible and stable throughout their manipulation. Chalcone nanoemulsions were developed using the spontaneous emulsification technique. The NE were characterized regarding their particle size, polydispersion index (PDI), and zeta potential. The results showed NE with spherical shape, absolute values of zeta potential were higher than 30 mV and homogeneous distribution pattern (PDI < 0.3). Dynamics light scattering (DLS) analysis showed similar hydrodynamic rays, i.e., 180 nm (trans-chalcone NE) and 178 nm (NE containing 3'-(trifluormethyl)-chalcone, in addition to presenting encapsulation efficiency values close to 100 %. Subsequently, the NE were added to a polymeric solution of polyvinyl alcohol (PVA) and processed via the electrospinning technique affording a PVA matrix (15 %, w/v) nanofiber containing the chalcones NE at 1 mg.mL. In a follow-up experiment, the skin permeation assay of the PVA matrix-chalcone NE was performed in vitro using Franz type diffusion cells and porcine ear as biological model of study. The results showed that the treatments with the nanofibers containing the chalcone NE were retained mainly in the stratum corneum, while the NE suspensions containing chalcone were retained in the epidermis and dermis. This result is thought to be relevant, since parasites are located mainly in the dermis. Further, in vitro assay against the amastigote form of L. (L) amazonensis, showed IC values to trans-chalcone and 3'-(trifluormethyl)-chalcone of 24.42 ± 6.76 μg.mL and 15.36 ± 4.61 μg.mL, respectively. In addition to improving the solubility of the compounds tested in culture medium without using organic solvents, chalcones in nano-emulsified form reduced the IC to 9.09 ± 1.24 μg.mL (trans-chalcone) and 10.27 ± 2.27 μg.mL (3'-(trifluormethyl)-chalcone) which confirmed the potential of the nanoemulsion containing chalcone for cutaneous leishmaniasis treatment.